I built a few sb oval track motors for the local dodge dealer around 92-94.
For one of the builds we used the MP high performance/high swirl bare heads, and at that time what we got was just a pair of 308 castings. They were cheaper to buy through MP than through the parts dept as a replacement part at the time.

Anyway, I do all the same prep we did to all the other heads we were using, which were just various used OE 360 castings, and we discovered after these were done and installed on the block that that rocker stands were machined too close to the valves.
We were using Norris stainless rockers, and with these heads the rocker body wouldn't fit between the shaft and retainer.
Pulled a couple springs/retainers, and the rollers were basically hanging off the edge of the valves.
We had the stands cut off, and some new stands fabbed up that relocated the shafts back to the correct position.

I find it hard to believe the set we had were the only ones made like that(especially knowing how much variation I've seen in how stage 6's are machined).

Sounds to me like if you're intent on using those heads, they're likely going to need to make a trip somewhere to have some stands made to get the rocker geometry sorted out.
I wouldn't count on being able to just buy some off the shelf parts to get it done.